real answer is. The reply could not be completely given by any one until after the invention of the spectroscope in 1861—some forty years ago.
Copernicus taught the heliocentric theory—that the planets revolved about the sun, as we know that they do. In 1616 his books were placed upon the index, there to remain 'until corrected.' The action of the Congregation of the Index was an incident in the distressing history of Galileo. It was not taken, however, until the congregation had consulted leading astronomers and had obtained their verdict that the heliocentric theory was without foundation. The pseudo-science of the Aristotelian professors (nearly all of whom were inimical to Galileo for personal as well as philosophical reasons) was opposed to the science of Copernicus. With this verdict in their minds it is not strange that the congregation should have proceeded against Galileo for heresy.
The system of Copernicus was proposed in 1543. It was true in its grand outlines; it was erroneous in many details. It was not proved till Galileo's discoveries of 1610. Tycho Brahé, the greatest authority of his time, expressly rejected it as absurd, and proposed a new system of the world in 1587. Kepler rejected Tycho's system and proposed his own first system (which was entirely erroneous) in 1597. He proposed his second system in 1609. How could theological doctors know that at last Kepler had reached the true system of the world by his glorious discoveries of 1609? His first theory was utterly without foundation. How could theologians, his contemporaries, possibly know that the second was not in like case? How could they know that he would not live to produce a third? Let us put ourselves in their place. What should we, being doctors of the church, ignorant of physical science, and profoundly indifferent to science as such, have done? Is it too much to conclude that our action would have been precisely that of the churchmen of that day? That we should have done precisely as the Romans did; as Luther, Melancthon and other protestants had earlier done? Kepler believed that all comets moved in straight lines; that the planets were sometimes repelled, sometimes attracted, by the sun; that each planet had a soul to guide it on its path; that all the planets sang together—Mercury, soprano; Venus, contralto; Mars, tenor; Jupiter and Saturn, bass. How much of all this was the church bound to accept? All of it is false. How could theological doctors possibly sift the false from the true?
The correspondence of Kepler and Galileo on the question of the tides is interesting in this connection. Kepler likens the earth to an animal, and the tides to its breathings and inbreathings, and says they follow the moon. Galileo laughs at him for this and declares that it is mere superstition to connect the moon with the tides. Ought the Roman church to have accepted Galileo's dictum?
- This fact is omitted by the warfare-of-science books.